The subject matter of this application relates to a method of identifying speakers in a home theater system.
A typical home theater system comprises a display unit, a DVD player or other signal source, an audio video control receiver, and multiple speakers. A so-called 7.1 channel system uses eight speakers, namely a center speaker, a subwoofer and six surround speakers (right and left front, right and left fill and right and left rear). The home theater system includes a home theater decoder which creates eight digital audio signals, which are assigned to the eight speakers respectively, from data that the DVD player reads from the disk. We will assume for the purpose of this discussion that the home theater decoder is integrated in the DVD player but it could be elsewhere in the system.
The home theater decoder combines the digital audio signals in four pairs, each pair running on an I2S serial bus. The I2S serial bus signal is composed of a succession of frames, each of which contains 32 left channel bits followed by 32 right channel bits. The labeling of the two groups of 32 bits as left channel and right channel is conventional but arbitrary, in that there is no industry standard that requires the left channel component of a two-channel audio signal to be encoded in the first group of bits of the I2S frame and the corresponding right channel component to be encoded in the second group of bits of the I2S frame. In a 7.1 channel home theater decoder having four I2S buses, I2S bus 0 might convey the signals created for the right front and left front speakers, bus 1 might convey the signals for right fill and left fill, bus 2 the signals for right rear and left rear, and bus 3 the signals for center and subwoofer. However, there is no industry standard for mapping speaker position to I2S bus channel. The DVD player transmits the four I2S serial bus signals over a digital communication medium to the receiver, which separates the four two-channel signals to generate eight digital audio signals and converts the digital audio signals to analog form for driving the eight speakers respectively. The system may employ wired speaker connections, in which case the receiver has at least eight pairs of speaker terminals from which wires run to the eight speakers respectively.
The subwoofer conveys low frequency information and the placement of the subwoofer and the timing of the audio signal for driving the subwoofer are not critical to satisfactory operation of the home theater system. However, optimum performance of the home theater system requires that the acoustic signals received from the other seven speakers at a listening location have the proper timing relationships, and consequently the receiver includes a facility for selectively delaying the audio signals supplied to the speakers to achieve the proper timing relationships among the acoustic signals.
The procedures for proper adjustment of the audio signal delays are so challenging to many would-be users of home theater systems that a large proportion of the receivers and multi-channel speaker systems that are purchased are returned to the stores without ever being properly installed.